CN112327319A - Solid-state laser radar detection method and system based on cyclic frequency shift ring - Google Patents
Solid-state laser radar detection method and system based on cyclic frequency shift ring Download PDFInfo
- Publication number
- CN112327319A CN112327319A CN202011238233.7A CN202011238233A CN112327319A CN 112327319 A CN112327319 A CN 112327319A CN 202011238233 A CN202011238233 A CN 202011238233A CN 112327319 A CN112327319 A CN 112327319A
- Authority
- CN
- China
- Prior art keywords
- frequency
- optical
- signal
- optical signal
- band
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000001514 detection method Methods 0.000 title claims abstract description 46
- 125000004122 cyclic group Chemical group 0.000 title claims abstract description 43
- 230000003287 optical effect Effects 0.000 claims abstract description 250
- 239000006185 dispersion Substances 0.000 claims abstract description 42
- 238000005516 engineering process Methods 0.000 claims abstract description 27
- 238000012545 processing Methods 0.000 claims abstract description 13
- 238000009826 distribution Methods 0.000 claims abstract description 10
- 238000006243 chemical reaction Methods 0.000 claims abstract description 7
- 239000007787 solid Substances 0.000 claims abstract description 5
- 238000010408 sweeping Methods 0.000 claims description 51
- 238000000034 method Methods 0.000 claims description 13
- 230000001360 synchronised effect Effects 0.000 claims description 9
- 239000013307 optical fiber Substances 0.000 claims description 6
- 239000004973 liquid crystal related substance Substances 0.000 claims description 5
- 230000003321 amplification Effects 0.000 claims description 3
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 3
- 238000007493 shaping process Methods 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 2
- 230000003595 spectral effect Effects 0.000 claims description 2
- 238000005259 measurement Methods 0.000 abstract description 2
- 238000013507 mapping Methods 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 238000012937 correction Methods 0.000 description 4
- 238000011161 development Methods 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 238000003491 array Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000003111 delayed effect Effects 0.000 description 2
- 239000000523 sample Substances 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 238000005299 abrasion Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000004038 photonic crystal Substances 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
- G01S17/42—Simultaneous measurement of distance and other co-ordinates
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/481—Constructional features, e.g. arrangements of optical elements
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/481—Constructional features, e.g. arrangements of optical elements
- G01S7/4814—Constructional features, e.g. arrangements of optical elements of transmitters alone
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/481—Constructional features, e.g. arrangements of optical elements
- G01S7/4817—Constructional features, e.g. arrangements of optical elements relating to scanning
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/481—Constructional features, e.g. arrangements of optical elements
- G01S7/4818—Constructional features, e.g. arrangements of optical elements using optical fibres
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Computer Networks & Wireless Communication (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Electromagnetism (AREA)
- Optical Radar Systems And Details Thereof (AREA)
Abstract
The invention discloses a solid laser radar detection method based on a cyclic frequency shift ring, which comprises the steps of sending a narrow-band frequency sweep optical signal into the cyclic frequency shift ring to obtain a wide-band frequency sweep optical signal, dividing the wide-band frequency sweep optical signal into two paths, using one path as a reference optical signal, and sending the other path into a dispersion unit through an optical collimating mirror; the dispersion unit controls different frequency sweep frequency sub-signals of the broadband sweep frequency signal to sequentially point to different directions in a free space to obtain a series of detection optical signals pointing to different directions; the detection optical signal meets a target and then is reflected back to the dispersion unit, and is combined with the reference optical signal into a path of optical signal to be detected after being received by the optical collimating mirror; after the photoelectric conversion and signal acquisition of the optical signal to be detected are finished, target space distribution information can be obtained based on a signal processing algorithm. The invention also discloses a solid-state laser radar detection system based on the cyclic frequency shift ring, which can simultaneously realize high-precision measurement of target angle and distance information by the optical cyclic frequency shift and optical wavelength dispersion technology.
Description
Technical Field
The invention relates to a solid-state laser radar detection method, in particular to a solid-state laser radar detection method and a solid-state laser radar detection system adopting a cyclic frequency shift ring and a wavelength (frequency) dispersion technology.
Background
The laser radar is widely applied to the fields of automatic driving, intelligent robots, three-dimensional sensing and the like. In order to obtain three-dimensional/two-dimensional spatial distribution information of a detection scene/target, a laser radar system mostly adopts a mechanical scanning mode to realize spatial two-dimensional/one-dimensional scanning of a laser beam so as to obtain target angle information, and obtains target distance information based on a pulse time arrival technology (see [ j.liu, q.sun, z.fan, y.jia, "TOF laser Development in autonomus vessel," IEEE 3rd optical-optics Global Conference,2018. ]). However, the mechanical scanning mode based scheme has limited application in high precision, high stability and long service life due to the complex structure, easy abrasion, and limited stability and service life of mechanical parts. Meanwhile, solutions of solid-state beam control technologies such as silicon optical phased arrays, liquid crystal waveguides, and photonic crystal waveguides have been rapidly developed, and these technologies use electronic control to realize rapid scanning of laser beams, and have better stability and robustness compared with mechanical scanning (see [ c.poulton, a.yaacobi, d.cole, etc. "thermal solid-state LIDAR with silicon optical phase arrays" "Optics Letters, vol.42, No.20, pp.4091-4094,2017 ]), however, the comprehensive performance and the system maturity of related technologies are currently limited. However, the solid-state beam control technology still attracts the researchers to promote the development of the technology to the practical direction due to the potential advantage characteristics. For distance information, the frequency modulation continuous wave heterodyne method has a higher dynamic range and detection sensitivity than the pulse arrival time method, and has a certain resistance effect on natural light interference, so that the method is widely researched. In summary, the combination of the solid-state beam steering technique and the frequency modulated continuous wave heterodyne method will likely promote the further development of high performance laser radar. A laser radar scheme based on a vertical cavity laser (VCSEL) broadband Swept Source is proposed by a paper (see [ M.Okano, C.Chong, sweep Source Lidar: sinusoidal FMCW ranging and non-mechanical beam steering with a wideband Swept Source, "Optics Express, vol.28, No.16, pp.23898-23915,2020 ], and the system is simple in structure and high in efficiency by segmenting the broadband continuous Swept Source and utilizing a wavelength dispersion mechanism to achieve simultaneous acquisition of two-dimensional information of a target distance and an angle. However, the VCSEL-based swept source has nonlinearity and limited coherence length, so that the scheme requires a more complex nonlinear correction circuit and nonlinear correction algorithm to compensate for the nonlinearity, and the detection distance is also limited.
Aiming at the problems, the invention provides a new solution. The method is based on the optical cyclic frequency shift technology to expand the narrow-band frequency-swept optical signal with high linearity and high coherence length to broadband frequency sweep, and realizes one-dimensional optical beam scanning based on wavelength dispersion without a nonlinear correction circuit and algorithm. And target distance information is acquired based on a frequency modulation removing technology, and the system can realize long-distance target detection due to the higher coherence length of a signal source. In addition, because the parameters of the cyclic frequency shift loop are flexible and adjustable, the laser radar system has higher flexibility and can be quickly and flexibly switched in the face of different detection scenes.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the method overcomes the defects of the prior art, realizes the generation of the detection signal of the broadband laser radar based on the optical cycle frequency shift technology, realizes the space scanning of the laser beam based on the wavelength dispersion technology, and realizes the acquisition of the high-resolution target distance information based on the optical domain frequency modulation technology. The system generates linear sweep frequency signals with high linearity and good coherence, can simultaneously acquire two-dimensional information of angles and distances, and greatly improves the working efficiency of the radar system.
The invention specifically adopts the following technical scheme to solve the technical problems:
a solid-state laser radar detection method based on a cyclic frequency shift loop specifically comprises the following steps:
sweep the narrow band of the optical signal fL_1Sending the frequency signals into a cyclic frequency shift ring to obtain a frequency band f containing N frequency sweepsL_i(i is 1,2, …, N), dividing the broadband swept optical signal into two paths, wherein one path is used as a reference optical signal, and the other path is sent to the dispersion unit through the optical collimating mirror; dispersion (dispers)The unit controls different frequency sweep frequency sub-band signals of the broadband sweep frequency optical signal to sequentially point to different directions in a free space to obtain a series of detection optical signals pointing to different directions; the detection light signal meets a target and then is reflected back to the chromatic dispersion unit to obtain a receiving light signal, and the receiving light signal is received by the light collimating mirror and then is combined with the reference light signal into a path of light signal to be detected; and the optical signal to be detected completes photoelectric conversion to obtain an intermediate frequency electric signal carrying target information, and the high-precision two-dimensional spatial distribution information of the target can be obtained by collecting and processing the intermediate frequency electric signal.
Preferably, the specific working mode of the cyclic frequency shift loop is as follows: narrow-band frequency-sweeping optical signal fL_1The signal enters a first input end of a 2 multiplied by 2 optical coupler and is divided into two paths, a first output end of the 2 multiplied by 2 optical coupler outputs a signal as a frequency sweep sub-band signal in a sub-period of a broadband frequency sweep optical signal, and a second output end of the 2 multiplied by 2 optical coupler outputs a signal which is subjected to frequency shift delta f by an electro-optical frequency shifter to obtain a narrow-band frequency sweep optical signal fL_2(ii) a The narrow-band frequency-sweeping optical signal enters the second input end of the 2 multiplied by 2 optical coupler and the narrow-band frequency-sweeping optical signal f after optical amplification and optical delayL_1Carrying out the same operation; when the Nth narrow-band frequency-sweeping optical signal fL_NAfter the generation, an optical switch in the cyclic frequency shift loop is controlled to disconnect the loop, that is, the generation of the broadband frequency-sweeping optical signal with the period of NT and the bandwidth of (N-1) Δ f + B is completed, wherein B and T are the bandwidth and the sub-period of the frequency-sweeping sub-band signal respectively.
Further, the sub-band signal f of the broadband swept optical signalL_i(i ═ 1,2, …, N) with the same bandwidth B and period T adjustable; the frequency interval delta f of the center carrier frequency of the sweep frequency sub-band signal is adjustable, and the requirement that delta f is more than or equal to B is met between the frequency interval delta f and the bandwidth B of the sweep frequency sub-band signal; the detection distance resolution can be changed by adjusting the bandwidth B of the subband signals, and the detection angle interval can be changed by adjusting the frequency interval delta f; narrow-band frequency-sweeping optical signal fL_1The output signal starts at NT intervals, synchronized with the switching period NT of the optical switch.
Further, the specific working mode of the dispersion unit is as follows: frequency sweep sub-band f based on wavelength (frequency) dispersion principleL_iAfter passing through the dispersion unit in turn, the optical beam is transmitted in spaceThe directions are sequentially and respectively pointed to thetaiRealizing one-dimensional beam scanning in space, wherein the beam scanning range is delta theta-thetaN-θ1Delta theta can be expanded by increasing the bandwidth (N-1) of the broadband swept optical signal, delta f + B.
Preferably, the dispersion unit is a diffraction grating, a prism, a liquid crystal;
preferably, the narrow-band swept-frequency optical signal is obtained by modulating a single-frequency laser signal by a linear frequency modulation electrical signal through an electro-optical modulator; the electro-optical modulator comprises a Mach-Zehnder modulator, a phase modulator, a double-parallel Mach-Zehnder modulator and an intensity modulator; according to the type of the adopted electro-optical modulator, an optical filter can be selectively cascaded behind the modulator; by selecting the high-order modulation sideband, the bandwidth of the narrow-band frequency-sweeping optical signal can realize frequency multiplication relative to the bandwidth of the linear frequency-modulated electrical signal.
Further, the method also comprises a target three-dimensional information acquisition step: and combining the two-dimensional space distribution information with information acquired by a mechanical scanning technology to acquire target three-dimensional information, wherein the mechanical scanning technology comprises a micro-electromechanical scanning mirror, a galvanometer scanner, a polygon mirror scanner and a servo motor.
The following technical scheme can be obtained according to the same invention concept:
a cyclic frequency shift loop based solid state lidar detection system comprising:
a swept-frequency light source for generating a narrow-band swept-frequency optical signal fL_1；
A cyclic frequency shift loop for generating a frequency band f containing N swept frequenciesL_i(i ═ 1,2, …, N) broadband swept optical signals;
the first optical coupler is used for dividing the broadband frequency-sweeping optical signal output by the cyclic frequency shift ring into two paths, wherein one path is used as a reference optical signal, and the other path is used as a detection optical signal;
the second optical coupler is used for combining the reference optical signal and the received optical signal into a path to obtain an optical signal to be detected;
the optical circulator is provided with a port 1 connected with the first optical coupler and used for receiving the detection optical signal, a port 2 connected with the collimating mirror and used for sending the detection optical signal to the collimating mirror and receiving the receiving optical signal obtained by the collimating mirror, and a port 3 connected with the second coupler and used for sending the receiving optical signal to the second optical coupler;
the collimating mirror is used for transmitting the broadband swept optical signal to the dispersion unit and receiving a target echo signal from the dispersion unit to obtain a received optical signal;
the dispersion unit is used for enabling the broadband frequency-sweeping optical signal to point to different directions in space respectively at different frequencies and receiving target echo signals from different directions;
the low-frequency photoelectric detector is used for photoelectrically converting an optical signal to be detected into a medium-frequency electric signal carrying target information;
the signal acquisition and processing unit is used for performing analog-to-digital conversion on the intermediate-frequency electric signal, performing solid-state laser radar digital signal processing and extracting target information;
and the synchronous control unit is used for sending synchronous and control signals to the sweep frequency light source, the cyclic frequency shift ring and the signal acquisition and processing unit.
Preferably, the cyclic frequency shift loop comprises:
the system comprises a plurality of cascaded or single double-parallel Mach-Zehnder modulators, a plurality of optical fiber amplifiers and a plurality of optical fiber amplifiers, wherein the cascaded or single double-parallel Mach-Zehnder modulators are used for sequentially shifting the frequency of a series of frequency sweeping sub-band signals to generate frequency shifting optical signals;
the frequency shift signal source is used for generating a frequency shift signal for driving the frequency shift of the input signals of the plurality of cascaded or single double-parallel Mach-Zehnder modulators;
the optical amplifier is used for amplifying the frequency shift optical signal;
the optical delay line is used for delaying the amplified frequency shift optical signal;
the optical switch is used for controlling the on-off state of the cyclic frequency shift ring;
the 2 x 2 optical coupler is connected with the first input end of the frequency sweeping light source, the second input end of the frequency sweeping light source is connected with the optical switch, the first output end of the frequency sweeping optical coupler is used for outputting a series of generated frequency sweeping sub-band signals from the cyclic frequency shifting ring, and the second output end of the frequency sweeping optical coupler is connected with the input end of the double parallel Mach-Zehnder modulator;
and the optical beam shaper is used for filtering out-of-band noise of the broadband frequency-swept optical signal generated by the cyclic frequency shift ring and shaping the spectral flatness of the broadband frequency-swept optical signal.
Furthermore, the narrow-band frequency-sweeping optical signal is obtained by modulating a single-frequency laser signal by a linear frequency modulation electric signal through an electro-optic modulator; the electro-optical modulator comprises a Mach-Zehnder modulator, a phase modulator, a double-parallel Mach-Zehnder modulator and an intensity modulator; according to the type of the adopted electro-optical modulator, an optical filter can be selectively cascaded behind the modulator; by selecting the high-order modulation sideband, the bandwidth of the narrow-band frequency-sweeping optical signal can realize frequency multiplication relative to the bandwidth of the linear frequency-modulated electrical signal.
Further, a narrow-band swept optical signal fL_1The output signal starts at NT intervals, synchronized with the switching period NT of the optical switch.
Further, the dispersion unit is a diffraction grating, a prism, a liquid crystal.
And furthermore, the system also comprises a mechanical scanning device, and the two-dimensional space information and the information scanned by the mechanical scanning device are combined to realize the acquisition of the target three-dimensional information, wherein the mechanical scanning device is a micro-electromechanical scanning mirror, a galvanometer scanner, a polygon mirror scanner and a servo motor.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
1) the invention realizes the generation of the broadband frequency sweeping signal based on the optical cycle frequency shifting technology, and the broadband frequency sweeping signal inherits the high linearity and the long coherence of the initial narrowband frequency sweeping optical signal. Therefore, the laser radar system does not need a complex nonlinear feedback control circuit, a nonlinear correction circuit and an algorithm, and the effective detection distance of the laser radar system can be increased.
2) The invention realizes the one-dimensional scanning of the space laser beam by a wavelength (frequency) dispersion technology, and a single dispersion unit can realize the mapping of the laser frequency-detection angle and finally realize the mapping of the intermediate frequency signal sub-period-detection angle; the scheme has the advantages of simple structure and high scanning speed, and can simultaneously realize high-precision and quick acquisition of two-dimensional information of target distance and angle.
3) The frequency interval of the optical signals of the frequency sweep sub-band can be controlled by the frequency shift signal source, the time interval of the optical signals of the frequency sweep sub-band can be controlled by optical fiber delay, the bandwidth and the signal duration of the optical signals of the frequency sweep sub-band can be controlled by adjusting the parameters of the initial narrow-band frequency sweep optical signals, and the parameters of the laser radar system can be accurately and flexibly adjusted to adapt to different detection scenes/targets.
Drawings
FIG. 1 is a schematic diagram of a solid state lidar system of the present invention;
FIG. 2 is a schematic block diagram of one embodiment of a solid state lidar system of the present invention;
FIG. 3 is a schematic diagram of a cyclic frequency shift loop in the solid-state lidar system of FIG. 2;
FIG. 4 is a diagram of mapping relationships between broadband swept frequency probe signals, broadband swept frequency receiver signals, sub-band swept frequency signals, offset angles of the sub-band swept frequency signals through a dispersion unit, detection of different range targets by beams at different angles, sub-period signal distributions of intermediate frequency electrical signals, and the like;
Detailed Description
Aiming at the defects of the prior art, the invention realizes the generation of the detection signal of the broadband solid-state laser radar based on the light circulation frequency shift technology, realizes the scanning of the laser beam based on the wavelength dispersion technology, and realizes the acquisition of the high-resolution target distance information based on the optical domain frequency modulation removal technology. The system generates linear sweep frequency signals, has high linearity and good coherence, can simultaneously realize the acquisition of angle and distance two-dimensional information without mechanical scanning, and greatly improves the working efficiency of the radar system.
The invention discloses a solid-state laser radar detection system based on a cyclic frequency shift ring, which comprises a sweep light source, a cyclic frequency shift ring, a first optical coupler, a second optical coupler, an optical circulator, a collimating mirror, a dispersion unit, a low-frequency photoelectric detector (LFPD), a signal acquisition and processing unit, a synchronous control unit and the like, as shown in figure 1.
Narrow-band frequency-sweeping optical signal f generated by frequency-sweeping light sourceL_1Sweeping the narrow band with the frequency of the optical signal fL_1Sending the frequency signals into a cyclic frequency shift ring to obtain a frequency band f containing N frequency sweepsL_i(1,2, …, N), the first optical coupler is to be broadThe optical signal with sweep frequency is divided into two paths, wherein one path is used as a reference optical signal, and the other path is introduced into the optical collimating mirror through the optical circulator and is sent into the dispersion unit; the dispersion unit controls different frequency sweep frequency sub-band signals of the broadband sweep frequency optical signal to sequentially point to different directions in a free space to obtain a series of detection optical signals pointing to different directions; the detection optical signal meets a target and then is reflected back to the chromatic dispersion unit to obtain a received optical signal, and the received optical signal and the reference optical signal are combined into a path of optical signal to be detected in a second optical coupler after being received by the optical collimating mirror; and the optical signal to be detected is subjected to photoelectric conversion by a low-frequency photoelectric detector to obtain an intermediate-frequency electric signal carrying target information, and the intermediate-frequency electric signal is acquired and subjected to signal processing to simultaneously obtain high-precision two-dimensional spatial distribution information of the target. The synchronous control unit controls the output period of the sweep frequency light source, the cycle period of the cycle frequency shift ring and the period of the signal acquisition and processing unit to be consistent.
In addition, the two-dimensional spatial distribution information is combined with a mechanical scanning technology, so that target three-dimensional information can be acquired; the mechanical scanning technology comprises a micro-electromechanical scanning mirror, a galvanometer scanner, a multi-surface mirror scanner and a servo motor.
For the public understanding, the technical scheme of the invention is further explained in detail by a specific embodiment:
as shown in fig. 2, the solid-state lidar detection system of the present embodiment includes: 1 linear frequency modulation signal source (LFM), 1 Phase Modulator (PM), 1 laser source (LD), 1 Optical Band Pass Filter (OBPF), 1 circulation frequency shift ring, 2 optical couplers (first optical coupler and second optical coupler), 1 Low Frequency Photoelectric Detector (LFPD), 1 optical circulator, 1 collimating mirror, 1 dispersion unit, 1 signal acquisition and processing unit, 1 synchronization control unit.
The schematic diagram of the cyclic frequency shift ring structure is shown in fig. 3, and includes: 2 x 2 optical coupler, double parallel Mach-Zehnder modulator, frequency shift signal source (FS), optical amplifier, optical delay line, optical switch and optical beam shaper (WS).
It should be noted that the swept source may be implemented using various known technologies, preferably,in this embodiment, a scheme of a chirp signal external modulation phase modulator is selected, and the swept-frequency light source is composed of a chirp signal source, a phase modulator, a laser, and an optical filter. The output instantaneous frequency of the linear frequency modulation signal source is fLFM＝f0A linear FM signal of + kt, and a carrier frequency of fCThe continuous wave optical signal of (2) can be obtained to contain an optical carrier frequency fCAnd multiple order swept sidebands fC±jfLFM(j is the order of the frequency sweep sideband), and the optical bandpass filter filters out one frequency sweep sideband of the modulated optical signal, and taking the positive second order as an example, the narrow-band frequency sweep optical signal f can be obtainedL_1＝fC+2fLFMThe time domain expression is:
wherein A is1For sweeping the optical signal f for a narrow bandL_1Amplitude of (f)0Is the starting frequency of the chirp signal, k is the chirp rate of the chirp signal, T1The time width of the chirp signal. The narrow-band frequency-sweeping optical signal is sent into a cyclic frequency shift ring, enters an optical coupler through a first input port of a 2 x 2 optical coupler and is divided into two paths, one path is output from a first output end of the 2 x 2 optical coupler, and the other path enters the ring of the cyclic frequency shift ring from a second output end.
Sending the narrow-band frequency-sweeping optical signal entering the cyclic frequency shift ring into a double-parallel Mach-Zehnder modulator, and realizing the carrier-restraining single-sideband modulation by a frequency shift signal with the frequency of delta f so as to realize the optical domain frequency shift; the narrowband frequency-swept optical signal after frequency shift is sent to an optical amplifier for amplification, and is delayed by a time delay tau through an optical time delay line0The delayed narrow-band frequency-sweeping optical signal is sent to the second input end of the 2 multiplied by 2 optical coupler after passing through the closed optical switch, and at the moment, the narrow-band frequency-sweeping optical signal fL_2The time domain expression is:
wherein A is2For sweeping the optical signal f for a narrow bandL_2The amplitude of (A) is T which is the sum of the time delay of each functional device in the cyclic frequency shift ring, the size of the cyclic frequency shift ring can be controlled by controlling an optical delay line, but the requirement of T is met1T or less, narrow band frequency sweep optical signal fL_2Same narrow band sweep optical signal fL_1The same is divided into two paths, one path is output from the first output end of the 2 multiplied by 2 optical coupler, and the other path enters the ring of the cyclic frequency shift ring from the second output end. Narrow-band frequency-sweeping optical signal f entering ringL_2Experience and narrow-band swept optical signal fL_1And after the Nth frequency-shifted narrow-band frequency-sweeping optical signal passes through the optical switch, the optical switch is switched off, and one circulation is completed to obtain the broadband frequency-sweeping optical signal. The wideband swept-frequency optical signal may be represented as:
wherein A isiFor sweeping the optical signal f for a narrow bandL_iWith the period of the broadband swept optical signal NT. The broadband sweep frequency optical signal is sent to an optical beam shaper to filter out-of-band noise, and the narrowband sweep frequency optical signal amplitude A of the broadband sweep frequency optical signal is subjected toiAnd after the consistency shaping, sending the optical fiber into a first optical coupler. The first optical coupler divides the shaped broadband frequency-sweeping optical signal into two paths, wherein one path is used as a reference optical signal, and the other path is used as a detection optical signal and sent to the optical circulator. The optical circulator sends the broadband swept optical signal into an optical collimating mirror, and the optical collimating mirror emits the broadband swept optical signal to a dispersion unit to become a detection optical signal. Based on the mapping relation between the frequency and the angle and the dispersion, the dispersion unit controls the narrow-band frequency-sweeping optical signals with different frequencies to sequentially emit to the direction thetaiSince the frequency of the narrowband swept signal increases with time, the angle θ isiWith the cycle time T (i-1) + T1A mapping relationship also exists. The detection light signal emitted to the space is reflected after meeting the target, the reflected signal is sent to the light collimating mirror through the dispersion unit in sequence to obtain a received light signal, and the light collimating mirror receives the received light signalAnd sending the optical signals into a second optical coupler through an optical circulator to be combined with the reference optical signals into a path to obtain the optical signals to be detected. Let the angle be thetaiThe delay difference between the received optical signal corresponding to the sub-period and the reference optical signal is tauiThen the optical signal to be detected can be expressed as:
wherein A isRiIn order to receive the amplitude of the optical signal sub-band signal, the optical signal to be detected is sent to a low-frequency photoelectric detector to be subjected to photoelectric conversion to obtain the amplitude tauiThe expression of the related intermediate frequency electric signal is as follows:
wherein A isRIiThe amplitude of the sub-period of the intermediate-frequency electric signal is acquired, and time-angle mapping and distance dimension information extraction are carried out, so that high-precision target two-dimensional distribution information can be obtained. For the sake of understanding, fig. 4 is a detailed diagram illustrating the measurement principle of the target distance information and the angle information and the frequency-angle mapping relationship of the broadband swept frequency probe signal.
In addition, the two-dimensional space information is combined with a mechanical scanning technology, so that target three-dimensional information can be acquired; the mechanical scanning technology comprises a micro-electromechanical scanning mirror, a galvanometer scanner, a multi-surface mirror scanner and a servo motor.
Finally, it should be noted that the above-mentioned list is only a specific embodiment of the present invention. The present invention is not limited to the above embodiments, and many variations are possible. All modifications which can be derived or suggested by a person skilled in the art from the disclosure of the present invention are to be considered within the scope of the invention.
Claims (10)
1. A solid-state laser radar detection method based on a cyclic frequency shift loop is characterized by comprising the following steps:
sweep the narrow band of the optical signal fL_1Sending the frequency signals into a cyclic frequency shift ring to obtain a frequency band f containing N frequency sweepsL_i(i is 1,2, …, N), dividing the broadband swept optical signal into two paths, wherein one path is used as a reference optical signal, and the other path is sent to a dispersion unit through a light collimating mirror; the dispersion unit controls different frequency sweep frequency sub-band signals of the broadband sweep frequency optical signal to sequentially point to different directions in a free space, and a series of detection optical signals pointing to different directions are obtained. The detection light signal meets a target and then is reflected back to the chromatic dispersion unit to obtain a receiving light signal, and the receiving light signal is received by the light collimating mirror and then is combined with the reference light signal into a path of light signal to be detected; and the optical signal to be detected completes photoelectric conversion to obtain an intermediate frequency electric signal carrying target information, and the high-precision two-dimensional spatial distribution information of the target can be obtained by collecting and processing the intermediate frequency electric signal.
2. The method of claim 1, wherein the cyclic frequency shift loop operates in a specific manner: narrow-band frequency-sweeping optical signal fL_1The signal enters a first input end of a 2 multiplied by 2 optical coupler and is divided into two paths, a first output end of the 2 multiplied by 2 optical coupler outputs a signal as a frequency sweep sub-band signal in a sub-period of a broadband frequency sweep optical signal, and a second output end of the 2 multiplied by 2 optical coupler outputs a signal which is subjected to frequency shift delta f by an electro-optical frequency shifter to obtain a narrow-band frequency sweep optical signal fL_2. Narrow-band frequency-sweeping optical signal fL_2Enters the second input end of the 2 multiplied by 2 optical coupler and the narrow-band frequency-sweeping optical signal f after optical amplification and optical delayL_1Carrying out the same operation; when the Nth narrow-band frequency-sweeping optical signal fL_NAfter the generation, an optical switch in the cyclic frequency shift loop is controlled to disconnect the loop, that is, the generation of the broadband frequency-sweeping optical signal with the period of NT and the bandwidth of (N-1) Δ f + B is completed, wherein B and T are the bandwidth and the sub-period of the frequency-sweeping sub-band signal respectively.
3. Method according to claim 2, characterized in that the subband signal f of the broadband swept optical signalL_i(i ═ 1,2, …, N) with the same bandwidth B and period T adjustable; the frequency interval delta f of the center carrier frequency of the sweep frequency sub-band signal is adjustable and is in the same band with the sweep frequency sub-band signalThe width B is required to satisfy that delta f is more than or equal to B. The change of the detection range resolution is realized by adjusting the bandwidth B of the subband signals, and the change of the detection angle interval is realized by adjusting the frequency interval delta f. Narrow-band frequency-sweeping optical signal fL_1The output signal starts at NT intervals, synchronized with the switching period NT of the optical switch.
4. The method of claim 1, wherein the dispersive unit operates in a specific manner as follows: frequency sweep sub-band f based on wavelength (frequency) dispersion principleL_iAfter sequentially passing through the dispersion unit, the light beam directions sequentially and respectively point to theta in spaceiRealizing one-dimensional beam scanning in space, wherein the beam scanning range is delta theta-thetaN-θ1Delta theta can be enlarged by increasing the bandwidth (N-1) delta f + B of the broadband frequency sweeping optical signal; the dispersion unit is diffraction grating, prism and liquid crystal.
5. The method of claim 1, wherein the narrow band swept optical signal is derived from a chirp electrical signal by modulating a single frequency laser signal with an electro-optic modulator; the electro-optical modulator is a Mach-Zehnder modulator, a phase modulator, a double-parallel Mach-Zehnder modulator or an intensity modulator. According to the type of the adopted electro-optical modulator, an optical filter is selectively cascaded behind the modulator; by selecting the high-order modulation sideband, the frequency multiplication of the narrow-band frequency-sweeping optical signal bandwidth is realized relative to the linear frequency modulation electrical signal bandwidth.
6. The method of claim 1, further comprising a target three-dimensional information acquisition step of: and combining the two-dimensional space distribution information with information acquired by a mechanical scanning technology to acquire target three-dimensional information, wherein the mechanical scanning technology comprises a micro-electromechanical scanning mirror, a galvanometer scanner, a polygon mirror scanner and a servo motor.
7. A solid state lidar detection system based on a cyclic frequency shift loop, comprising:
swept source for generating narrow wavelength lightOptical signal with frequency sweep fL_1。
A cyclic frequency shift loop for generating a frequency band f containing N swept frequenciesL_i(i ═ 1,2, …, N) broadband swept optical signals;
the first optical coupler is used for dividing the broadband frequency-sweeping optical signal output by the cyclic frequency shift ring into two paths, wherein one path is used as a reference optical signal, and the other path is used as a detection optical signal.
The optical circulator is provided with a port 1 connected with the first optical coupler and used for receiving the detection optical signal, a port 2 connected with the collimating mirror and used for sending the detection optical signal to the collimating mirror and receiving the receiving optical signal obtained by the collimating mirror, and a port 3 connected with the second coupler and used for sending the receiving optical signal to the second optical coupler;
the second optical coupler is used for combining the reference optical signal and the received optical signal into a path to obtain an optical signal to be detected;
the collimating mirror is used for transmitting the broadband swept optical signal to the dispersion unit and receiving a target echo signal from the dispersion unit to obtain a received optical signal;
the dispersion unit is used for enabling the broadband frequency-sweeping optical signal to point to different directions in space respectively at different frequencies and receiving target echo signals from different directions;
the low-frequency photoelectric detector is used for photoelectrically converting an optical signal to be detected into a medium-frequency electric signal carrying target information;
the signal acquisition and processing unit is used for performing analog-to-digital conversion on the intermediate-frequency electric signal, performing solid-state laser radar digital signal processing and extracting target information;
and the synchronous control unit is used for sending synchronous and control signals to the sweep frequency light source, the cyclic frequency shift ring and the signal acquisition and processing unit.
8. The system of claim 7, wherein the cyclic frequency shift loop comprises:
the system comprises a plurality of cascaded or single double-parallel Mach-Zehnder modulators, a plurality of optical fiber amplifiers and a plurality of optical fiber amplifiers, wherein the cascaded or single double-parallel Mach-Zehnder modulators are used for sequentially shifting the frequency of a series of frequency sweeping sub-band signals to generate frequency shifting optical signals;
the frequency shift signal source is used for generating a frequency shift signal for driving the frequency shift of the input signals of the plurality of cascaded or single double-parallel Mach-Zehnder modulators;
the optical amplifier is used for amplifying the frequency shift optical signal;
the optical delay line is used for delaying the amplified frequency shift optical signal;
and the optical switch is used for controlling the on-off state of the cyclic frequency shift ring.
The first input end of the 2 multiplied by 2 optical coupler is connected with the frequency sweeping light source, the second input end of the 2 multiplied by 2 optical coupler is connected with the optical switch, the first output end of the 2 multiplied by 2 optical coupler is used for outputting a series of generated frequency sweeping sub-band signals from the circulating frequency shifting ring, and the second output end of the 2 multiplied by 2 optical coupler is connected with the input end of the double parallel Mach-Zehnder modulator.
And the optical beam shaper is used for filtering out-of-band noise of the broadband frequency-swept optical signal generated by the cyclic frequency shift ring and shaping the spectral flatness of the broadband frequency-swept optical signal.
9. The system of claim 7, wherein the narrow band swept optical signal is obtained from a chirp electrical signal by modulating a single frequency laser signal with an electro-optic modulator; the electro-optical modulator comprises a Mach-Zehnder modulator, a phase modulator, a double-parallel Mach-Zehnder modulator and an intensity modulator; according to the type of the adopted electro-optical modulator, an optical filter is selectively cascaded behind the modulator; by selecting the high-order modulation sideband, the frequency multiplication of the narrow-band frequency-sweeping optical signal bandwidth is realized relative to the linear frequency-modulated electrical signal bandwidth. The dispersion unit is diffraction grating, prism and liquid crystal.
10. The system of claim 7, further comprising a mechanical scanning device, the mechanical scanning device being a micro-electromechanical scanning mirror, a galvanometer scanner, a polygon mirror scanner, a servo motor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011238233.7A CN112327319B (en) | 2020-11-09 | 2020-11-09 | Solid-state laser radar detection method and system based on cyclic frequency shift ring |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011238233.7A CN112327319B (en) | 2020-11-09 | 2020-11-09 | Solid-state laser radar detection method and system based on cyclic frequency shift ring |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112327319A true CN112327319A (en) | 2021-02-05 |
| CN112327319B CN112327319B (en) | 2023-12-19 |
Family
ID=74315559
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011238233.7A Active CN112327319B (en) | 2020-11-09 | 2020-11-09 | Solid-state laser radar detection method and system based on cyclic frequency shift ring |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112327319B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112799090A (en) * | 2021-03-25 | 2021-05-14 | 之江实验室 | Frequency reuse solid-state laser radar detection method and system |
| WO2022209789A1 (en) * | 2021-03-29 | 2022-10-06 | 株式会社小糸製作所 | Optical beam generation device and optical detector |
| CN116707650A (en) * | 2023-08-07 | 2023-09-05 | 四川省医学科学院·四川省人民医院 | Replication frequency shift system of broadband transient signal and implementation method thereof |
Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20020141697A1 (en) * | 2001-02-09 | 2002-10-03 | Daeyoul Yoon | Variable group delay unit and variable group delay optical fiber module |
| JP2009162678A (en) * | 2008-01-09 | 2009-07-23 | Mitsubishi Electric Corp | Laser radar system |
| CN104697557A (en) * | 2015-03-30 | 2015-06-10 | 南京大学 | Novel circular frequency shifting based BOTDR (Brillouin Optical Time Domain Reflectometer) coherent detection device and method |
| CN108375774A (en) * | 2018-02-28 | 2018-08-07 | 中国科学技术大学 | A kind of single photon image detecting laser radar of no-raster |
| US20190013862A1 (en) * | 2016-01-05 | 2019-01-10 | Shanghai Jiaotong University | Frequency synthesis-based optical frequency domain reflectometry method and system |
| US20190317194A1 (en) * | 2018-04-17 | 2019-10-17 | Santec Corporation | Lidar sensing arrangements |
| CN111106872A (en) * | 2019-12-31 | 2020-05-05 | 上海交通大学 | Device and method for generating optical frequency comb based on cascaded double parallel Mach-Zehnder modulators |
| CN111190160A (en) * | 2020-01-08 | 2020-05-22 | 南京航空航天大学 | Microwave photon multiband radar detection method and microwave photon multiband radar |
| CN111208531A (en) * | 2020-01-19 | 2020-05-29 | 中国科学技术大学 | Single photon imaging laser radar system based on wide-spectrum light source |
| CN111538028A (en) * | 2020-07-07 | 2020-08-14 | 之江实验室 | Polarization multiplexing microwave photon radar detection method and system based on photon sampling |
| CN111751827A (en) * | 2020-06-03 | 2020-10-09 | 之江实验室 | Microwave photon radar detection method and system based on light injection frequency modulation |
| CN111751812A (en) * | 2020-06-03 | 2020-10-09 | 之江实验室 | Microwave photon time division multiplexing MIMO radar detection method and system |
-
2020
- 2020-11-09 CN CN202011238233.7A patent/CN112327319B/en active Active
Patent Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20020141697A1 (en) * | 2001-02-09 | 2002-10-03 | Daeyoul Yoon | Variable group delay unit and variable group delay optical fiber module |
| JP2009162678A (en) * | 2008-01-09 | 2009-07-23 | Mitsubishi Electric Corp | Laser radar system |
| CN104697557A (en) * | 2015-03-30 | 2015-06-10 | 南京大学 | Novel circular frequency shifting based BOTDR (Brillouin Optical Time Domain Reflectometer) coherent detection device and method |
| US20190013862A1 (en) * | 2016-01-05 | 2019-01-10 | Shanghai Jiaotong University | Frequency synthesis-based optical frequency domain reflectometry method and system |
| CN108375774A (en) * | 2018-02-28 | 2018-08-07 | 中国科学技术大学 | A kind of single photon image detecting laser radar of no-raster |
| US20190317194A1 (en) * | 2018-04-17 | 2019-10-17 | Santec Corporation | Lidar sensing arrangements |
| CN111106872A (en) * | 2019-12-31 | 2020-05-05 | 上海交通大学 | Device and method for generating optical frequency comb based on cascaded double parallel Mach-Zehnder modulators |
| CN111190160A (en) * | 2020-01-08 | 2020-05-22 | 南京航空航天大学 | Microwave photon multiband radar detection method and microwave photon multiband radar |
| CN111208531A (en) * | 2020-01-19 | 2020-05-29 | 中国科学技术大学 | Single photon imaging laser radar system based on wide-spectrum light source |
| CN111751827A (en) * | 2020-06-03 | 2020-10-09 | 之江实验室 | Microwave photon radar detection method and system based on light injection frequency modulation |
| CN111751812A (en) * | 2020-06-03 | 2020-10-09 | 之江实验室 | Microwave photon time division multiplexing MIMO radar detection method and system |
| CN111538028A (en) * | 2020-07-07 | 2020-08-14 | 之江实验室 | Polarization multiplexing microwave photon radar detection method and system based on photon sampling |
Non-Patent Citations (2)
| Title |
|---|
| ENCI CHEN ET AL.: "2-μm Switchable dual-wavelength single-longitudinal-mode fiber laser based on a core-offset structure and carbon nanotube", APPLIED PHYSICS B, vol. 122, no. 11, XP036105332, DOI: 10.1007/s00340-016-6558-x * |
| 杨李杰等: "用于海洋监测的宽带数字相控阵关键 技术", 科技导报, vol. 35, no. 20 * |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112799090A (en) * | 2021-03-25 | 2021-05-14 | 之江实验室 | Frequency reuse solid-state laser radar detection method and system |
| CN112799090B (en) * | 2021-03-25 | 2021-08-03 | 之江实验室 | Frequency reuse solid-state laser radar detection method and system |
| WO2022209789A1 (en) * | 2021-03-29 | 2022-10-06 | 株式会社小糸製作所 | Optical beam generation device and optical detector |
| CN116707650A (en) * | 2023-08-07 | 2023-09-05 | 四川省医学科学院·四川省人民医院 | Replication frequency shift system of broadband transient signal and implementation method thereof |
| CN116707650B (en) * | 2023-08-07 | 2023-10-10 | 四川省医学科学院·四川省人民医院 | Replication frequency shift system of broadband transient signal and implementation method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| CN112327319B (en) | 2023-12-19 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US12038511B2 (en) | Precisely controlled chirped diode laser and coherent LIDAR system | |
| EP3465269A1 (en) | Coherent lidar system using tunable carrier-suppressed single-sideband modulation | |
| CN108287349B (en) | Microwave photon MIMO radar detection method and microwave photon MIMO radar system | |
| US11555923B2 (en) | LIDAR system with speckle mitigation | |
| CN112327319B (en) | Solid-state laser radar detection method and system based on cyclic frequency shift ring | |
| CN108919244B (en) | Microwave photon all-band radar detection method and microwave photon all-band radar | |
| CN110350980B (en) | Radar detection method and device based on bandwidth synthesis after microwave photon-assisted deskew | |
| CN111337902B (en) | Multi-channel high-repetition-frequency large-dynamic-range distance and speed measuring laser radar method and device | |
| CN112764050B (en) | Laser radar measurement method and laser radar system | |
| CN108761437B (en) | Microwave photon full polarization radar detection method and microwave photon full polarization radar | |
| CN112799090B (en) | Frequency reuse solid-state laser radar detection method and system | |
| Zhang et al. | Photonic approach to dual-band dual-chirp microwave waveform generation with multiplying central frequency and bandwidth | |
| CN111693988A (en) | Laser millimeter wave integrated distance and speed measuring radar method and device | |
| CN111948633B (en) | Flexible ultra-wideband digital microwave photon phased array radar | |
| CN113820688B (en) | Three-dimensional solid-state laser radar detection method and device based on double-optical-frequency comb | |
| CN111650601B (en) | High-resolution 3D imaging method and device for vehicle-mounted coherent laser radar | |
| CN110133616B (en) | Laser radar system | |
| CN109375200B (en) | Photon up-conversion-based optical carrier distributed radar detection method and device | |
| CN111965621A (en) | Method and device for generating radio frequency multi-chirp linear frequency modulation stepping signals | |
| US20230138571A1 (en) | Techniques for enhanced detection of distant objects | |
| CN113433556B (en) | Solid-state laser radar detection method and device based on Rotman optical lens | |
| JP2006162616A (en) | Heterodyne-based optical spectrum analysis using data clock sampling | |
| CN115015635A (en) | Microwave photon ultra-wideband real-time spectrum measurement method | |
| CN111886513B (en) | Laser radar device | |
| CN114355382A (en) | Microwave photon MIMO radar transmitting and receiving system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |